Add a new GetInstance() method for singleton classes used in chrome/browser files.

chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h"
 
+#include "base/singleton.h"
+
 void AppModalDialogQueue::AddDialog(AppModalDialog* dialog) {
   if (!active_dialog_) {
     ShowModalDialog(dialog);
     return;
   }
   app_modal_dialog_queue_.push(dialog);
 }
 
 void AppModalDialogQueue::ShowNextDialog() {
   AppModalDialog* dialog = GetNextDialog();
@@ skipping 14 matching lines @@
   if (active_dialog_)
     active_dialog_->ActivateModalDialog();
 }
 
 AppModalDialogQueue::AppModalDialogQueue()
     : active_dialog_(NULL), showing_modal_dialog_(false) {
 }
 
 AppModalDialogQueue::~AppModalDialogQueue() {}
 
+// static
+AppModalDialogQueue* AppModalDialogQueue::GetInstance() {
+  return Singleton<AppModalDialogQueue>::get();
+}
+
 void AppModalDialogQueue::ShowModalDialog(AppModalDialog* dialog) {
   // Be sure and set the active_dialog_ field first, otherwise if
   // ShowModalDialog triggers a call back to the queue they'll get the old
   // dialog. Also, if the dialog calls |ShowNextDialog()| before returning, that
   // would write NULL into |active_dialog_| and this function would then undo
   // that.
   active_dialog_ = dialog;
   showing_modal_dialog_ = true;
   dialog->ShowModalDialog();
   showing_modal_dialog_ = false;
 }
 
 AppModalDialog* AppModalDialogQueue::GetNextDialog() {
   while (!app_modal_dialog_queue_.empty()) {
     AppModalDialog* dialog = app_modal_dialog_queue_.front();
     app_modal_dialog_queue_.pop();
     if (dialog->IsValid())
       return dialog;
     delete dialog;
   }
   return NULL;
 }